While some people may see oysters as only a delicious delicacy, researchers are using them to understand the long term environmental impact of the Gulf oil spill. Oyster shells turn out to hold important clues about past ecological disasters. This hour, the importance of oysters – more than just good eating, these mollusks play a key role in the ecosystem. Guests PETER ROOPNARINE, a curator at the California Academy of Natural Science and PAUL CALLOMON, a collections manager at the Academy of Natural Science, tell us about reading oyster shells and the threats oysters face from pollution, climate change, acidification, overharvesting, and invasive species.